Abstract
Alumina-zinc oxide catalysts of various compositions were prepared from their nitrates by coprecipitation and the acidic and basic properties were measured by titrations with n-butylamine and benzoic acid using various indicators. The acidities (the numbers of acid sites) at H0 = −3.0 and H0 = −5.6 of Al2O3ZnO catalysts prepared from their nitrates, were found to be lower than those of Al2O3ZnO catalysts prepared from their chlorides by the same method. With the increase in ZnO content, the acidities per unit surface area decreased monotonously, whereas a maximum basicity was observed on Al2O3ZnO (1:1), the highest base strength (pKa) being 12.2. The activity change for alkylation of phenol with methanol was correlated well with the acidity change and the highest selectivity (almost 100%) for formations of ortho products, o-cresol and 2,6-xylenol, was observed on Al2O3ZnO (1:9). Isomerization of 1-butene was suggested to proceed on basic sites on Al2O3ZnO catalysts. In isomerization of 3-carene (I), the selectivity for formation of 2-carene (II) was more than 90% over Al2O3ZnO (1:9). From poisoning experiments with CO2 and pyridine, the active sites for formation of 2-carene were concluded to be both acidic and basic sites.
Published Version
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